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Distributed parameter systems (DPS) are systems defined on infinite dimensional spaces. This includes problems governed by partial differential equations (PDEs) and delay differential equations. In order to numerically implement a controller for a physical system we often first approximate the PDE and the PDE controller using some finite dimensional scheme. However, control design at this level will typically give rise to controllers that are inherently large-scale. This presents a challenge since we are interested in the design of robust, real-time controllers for physical systems. Therefore, a reduction in the size of the model and/or controller must take place at some point. Traditional methods to obtain lower order controllers involve reducing the model from that for the PDE, and then applying a standard control design technique. One such model reduction technique is balanced truncation. However, it has been argued that this type of method may have an inherent weakness since there is a loss of physical information from the high order, PDE approximating model prior to control design. In an attempt to capture characteristics of the PDE controller before the reduction step, alternative techniques have been introduced that can be thought of as controller reduction methods as opposed to model reduction methods. One such technique is LQG balanced truncation. Only recently has theory for LQG balanced truncation been developed in the infinite dimensional setting. In this work, we numerically investigate the viability of LQG balanced truncation as a suitable means for designing low order, robust controllers for distributed parameter systems. We accomplish this by applying both balanced reduction techniques, coupled with LQG, MinMax and central control designs for the low order controllers, to the cable mass, Klein-Gordon, and Euler-Bernoulli beam PDE systems. All numerical results include a comparison of controller performance and robustness properties of the closed loop systems. / Ph. D.

An attempt was made to reduce fuel costs of a diesel-electric locomotive by operating the locomotive in a periodic manner, as opposed to operating at a constant velocity. The periodic operation consisted of accelerating the locomotive in a high throttle position and then deccelerating at a low throttle position. An SD40 Locomotive was modeled to test the periodic operation. The periodic operation was actually found to offer no improvement in fuel performance over that of constant velocity operation. A modification to the diesel engine that takes advantage of the periodic operation is suggested that will give a better fuel performance. The modification to the engine would not be possible with constant velocity operation. With the modification, the periodic operation was found to save fuel over the constant velocity operation. A controller was then designed to implement the periodic operation. The key component of the controller is an observer to determine unknown hill forces. The controller was found to work successfully. / M.S.

The Control System Analysis and Design Package (CSADP) is a computer-aided design package for applying classical control system analysis and design tools to experimental frequency response measurements. CSADP allows the user to analyze and manipulate measured frequency response data, design control systems using these measurements, and determine the operational amplifier hardware required to implement the design. To perform these tasks, CSADP provides tools that allow the user to define problems using both frequency response data files and transfer function descriptions; generate Bode, Nyquist, and root-locus plots; and curve-fit frequency response data. The curve-fitting program uses novel data-scanning techniques for conditioning the data, and for predicting the model form and starting parameters. CSADP also allows the user to design compensators interactively using Bode and root-locus methods, and aids the user in selecting the required resistor and capacitor values needed for implementing the compensator using op-amp circuits. In addition, CSADP provides coefficients required to implement the compensator using selected digital algorithms. CSADP was used in the design of a velocity loop compensator for a precision diamond turning machine. Open loop frequency response data gathered from the machine was used as the basis for compensator design using Bode methods. The required compensator coefficients generated by the program were programmed into the servo for testing. Results showed that the closed loop response predicted by the program accurately matched the measured response. Estimates of natural frequencies provided by the model prediction program were within 5 percent of the actual values. Errors in estimates of the damping ratios for very lightly damped complex poles ranged from only 10 percent to 30 percent. CSADP is written in FORTRAN 77 and provides Tektronix (TEK) 4010/4014 compatible graphics output. / Master of Science

This paper presents a novel controller architecture and speed control design methodology suitable for low cost, low performance switched reluctance motor drives. By utilizing inexpensive components in a simple, compact architecture, a low cost controller is developed which achieves a performance level similar to many high performance controllers. A speed control design methodology is established and analyzed based on the linearized small signal model of the switched reluctance motor. This unique control methodology is simple and provides a starting point for further research into speed/current controller parameter design for switched reluctance motors. The analysis, design and realization of the speed controller are presented. The derivation of the design methodology for speed controlled, switched reluctance motor drives is discussed, along with computer simulations for verification. Experimental results utilizing the proposed architecture and design methodology verify the control design and performance capabilities of the speed controller system. / Master of Science

Cette thèse a été consacrée à l'étude des réseaux multi-terminaux haute tension à courant continu (MTDC). Les principales contributions étaient dans le domaine du contrôle automatique non linéaire, appliquées aux systèmes électriques, électronique de puissance et les sources d'énergie renouvelables. Le travail de recherche a été lancé avec l'intention de combler certaines lacunes entre la théorie et la pratique, en particulier: 1) d'enquêter sur diverses approches de contrôle pour le but d'améliorer la performance des systèmes MTDC; 2) d'établir des connexions entre la conception du contrôle empiriques existantes et analyse théorique; 3) d'améliorer la compréhension du comportement multi-échelle de temps des systèmes MTDC caractérisés par la présence de transitoires lents et rapides en réponse aux perturbations externes. En conséquence, ce travail de thèse peut être mis en trois domaines, à savoir la conception non linéaire de commande de systèmes MTDC, analyse des comportements dynamiques de système MTDC et l'application de systèmes MTDC pour le contrôle de fréquence des systèmes de climatisation. / This dissertation was devoted to the study of multi-terminal high voltage direct current (MTDC) networks. The main contributions were in the field of nonlinear automatic control, applied to power systems, power electronics and renewable energy sources. The research work was started with the intention of filling some gaps between the theory and the practice, in particular: 1) to investigate various control approaches for the purpose of improving the performance of MTDC systems; 2) to establish connections between existing empirical control design and theoretical analysis; 3) to improve the understanding of the multi-time-scale behavior of MTDC systems characterized by the presence of slow and fast transients in response to external disturbances. As a consequence, this thesis work can be put into three areas, namely nonlinear control design of MTDC systems, analysis of MTDC system's dynamic behaviors and application of MTDC systems for frequency control of AC systems.

The motivation of this research is to propose innovative nonlinear and optimal control design algorithms, which can be used in real life. The algorithms need to be computationally efficient, should deal with control constraints and should operate under state feedback. To show the efficacy of algorithms, automatic therapy for different cancer problems is chosen to be the field of application. In this thesis, first an advanced control design technique called ’optimal dynamic in-version’ has been successfully experimented with control constraints. The proposed approach has subsequently been shown to be quite effective in proposing automatic drug delivery schemes with simultaneous application of chemo and immunotherapy drugs for complete elimination of cancer cells in melanoma (a skin cancer) as well as glioma (a brain cancer). As per the current practice, the amount of drug dosages are generally given based on some apriori statistical study with a very small sample size, which in reality may either also lead to drug toxicity (due to excessive drug) or may become ineffective (due to insufficient drug) for a particular patient. Subject to the fidelity of the mathematical model (which has been taken from published literature), it has been shown in this thesis that nonlinear control theory can be used for computation of drug dosages, which can then be used in a feedback strategy, thereby customizing the drug for the patient’s condition, to cure the disease successfully. Next, attention has been shifted to impulsive control of systems. Such impulsive con-trol systems appear in many other applications such as control of swings, control of spacecrafts and rockets using reaction control system, radiotherapy in cancer treatment and so on. Two impulsive control design philosophies are proposed in this thesis. In one approach, recently proposed model predictive static programming (MPSP) has been extended for impulsive control systems and has been named as impulsive-MPSP (I-MPSP). In other approach, another recent development, namely the Pseudospectral method has been utilized to consider both the magnitude of the control impulses as well as the time instants at which they are applied as the decision variables. It can be noted, that to the best of the knowledge of the author, the time instants of control application, being considered as decision variables is being proposed for the first time in the nonlinear and optimal control framework. Both I-MPSP and Pseudospectral methods are computationally quite efficient and hence can be used for feedback control (I-MPSP happens to be computationally more efficient than the Pseudospectral method). Applicability of the proposed extensions have been shown by solving various benchmark problems such as (i) a scalar linear problem, (ii) Van der Pol’s oscillator problem and (iii) an inverted pendulum problem. Finally the applicability of the proposed I-MPSP strategy has been shown by solving challenging problems such as radiotherapy treatment of head and neck and adenocarcimona cancers. Radio-therapy model is considered with oxygen effect, in which radiosensitivity parameters are considered in different forms. Head and neck cancer is considered with constant radiosensitivity parameters and adenocarcinoma is considered with constant, linear, quadratic and saturation model of radiosensitivity parameters. Note that toxicity constraints on normal tissue, which are nonlinear control constraints, are also successfully incorporated in this control design.

With the growth of renewable energy usage and energy storage adoption in recent decades, people have started to reevaluate the possible roles of dc systems in current and future electrical systems. The dc voltage distribution has been applied in various applications, such as data centers and aircraft industry, for high efficiency and power density. However, for some applications such as subsea gas and oil fields, and ocean observatory systems, the dc current distribution is preferred over dc voltage distribution for its low cost and robustness against cable faults. Design and control of dc power distribution systems for different applications is an emerging research area with complex technical challenges. This dissertation solves the technical challenges in analysis, design, modeling, control and protection of series resonant converters (SRCs) for dc current distribution applications. An optimum design that has high efficiency, high reliability, and minimum required control efforts for the SRC with constant input current has been achieved and demonstrated by applying the analysis and design procedures developed in this dissertation. The modeling and analysis presented in this dissertation represents an operating condition that has not been studied in the literature and could be easily extended to other resonant converter topologies. Explicit analytical expressions have been provided for all key transfer functions, including input impedance and control-to-output, offering valuable resources to design feed-back regulation and to evaluate system stability. Based on the control strategies and control design presented in this dissertation, stable and reliable operation of dc current distribution systems with long distance cable has been achieved and demonstrated. The proposed analysis, design procedure, stability evaluation, control strategy and protection techniques in this dissertation can be applied to a wide range of similar scenarios as well, which greatly increases their value.

<p>Examensarbetet syftar till att jämföra nya alternativ till olika system för användning i laborationer i reglerteknikkurser för olika studentkategorier. Det skall utredas vilket av ett antal alternativ till mjukvaruplattformar som är bäst lämpat att användas vid reglerteknikundervisningen i ITN:s reglerlaboratorium vid Linköpings universitet. Tidigare laborationer i berörda kurser skall även modifieras så att dessa kan genomföras i de nya systemen.</p><p>Examensarbetet resulterade i en rad modifierade laborationer och system att tillämpa i dessa. De nya systemen medför att all reglering sköts direkt från en dator istället för tidigare variant med externa apparater som programmeras. På så sätt kan större fokus läggas på regleringen i sig och inte de system som tillämpas för att utföra den.</p> / <p>The purpose of this thesis work is to compare new alternatives for different systems to use in laborations, in courses offered in control system design, for different types of students. The intention is to investigate which of a number of software platform alternatives are best suited for these purposes. Current laborations are to be modified to be viable in the new systems.</p><p>The project resulted in a number of modified laborations and control systems to use in these. The new solutions are made so that all of the control is done by one computer, as opposed to the previous solution where external units had to be programmed and controlled. This way, the laborations can focus more on the control theory and less on the systems used to realize it.</p>

Examensarbetet syftar till att jämföra nya alternativ till olika system för användning i laborationer i reglerteknikkurser för olika studentkategorier. Det skall utredas vilket av ett antal alternativ till mjukvaruplattformar som är bäst lämpat att användas vid reglerteknikundervisningen i ITN:s reglerlaboratorium vid Linköpings universitet. Tidigare laborationer i berörda kurser skall även modifieras så att dessa kan genomföras i de nya systemen. Examensarbetet resulterade i en rad modifierade laborationer och system att tillämpa i dessa. De nya systemen medför att all reglering sköts direkt från en dator istället för tidigare variant med externa apparater som programmeras. På så sätt kan större fokus läggas på regleringen i sig och inte de system som tillämpas för att utföra den. / The purpose of this thesis work is to compare new alternatives for different systems to use in laborations, in courses offered in control system design, for different types of students. The intention is to investigate which of a number of software platform alternatives are best suited for these purposes. Current laborations are to be modified to be viable in the new systems. The project resulted in a number of modified laborations and control systems to use in these. The new solutions are made so that all of the control is done by one computer, as opposed to the previous solution where external units had to be programmed and controlled. This way, the laborations can focus more on the control theory and less on the systems used to realize it.